Studies of human biology of vanishing primitive societies focus on neurological development and learning patterns in diverse cultural experiments in the human condition found in such isolated groups. Opportunistic investigation of problems phrased by man in isolation is the basis of approach from which most of our studies evolved: kuru-CJD, HIV (AIDS), HTLV-I slow virus infections of the CNS, aging and Alzheimer's, VE, A LS/PD. Techniques of molecular genetics, biochemistry, immunology, virology, and field epidemiologic, clinical, linguistic and behavioral studies in cultural isolates and genetic and/or geographically isolated primitive bands yield more easily interpretable data than in cosmopolitan societies. Data and specimens from expeditions to Micronesia, Melanesia, Polynesia, South America, Asia and Africa proved valuable in recent HIV (AIDS), HTLV-I, Hantavirus, JC virus of PML and herpesvirus, CMV and EBV studies. Studies on nutrition, reproduction, fertility, age of puberty and aging, genetic distance and pleomorphisms, unusual and odd higher cortical functions in language learning, cognitive styles, computation (calculation without words or numbers) and culturally modified sexual behavior elucidate alternative forms of neurologic functioning for man which we are unable to investigate once the natural cultural experiments in primitive human isolates are amalgamated into the cosmopolitan community of man. Foci of high incidence of kuru, ALS/PD, HTLV-I myelopathy, epilepsy, familial parkinsonism, Viliuisk encephalopathy, other CNS degenerations, hysterical disorders, schizophrenia, bipolar psychoses, neoplasms, goiter, cretinism, rheumatoid diseases, diabetes, asthma, chronic lung disease, malaria, filariasis, leprosy, cysticercosis, and other infections in these isolated groups have yielded widely significant discoveries. HFRS caused by hantaviruses in Asia, USSR, Europe and newly recognized hantaviruses in the U.S. are studied. Human evolution and adaptability to high altitude, wet or arid climes, variable food supply, mineral deficiencies, toxic exposures and responses to severe diseases or social/psychological stress are studied in appropriate population. Thus, HTLV-l and HIV retroviruses as causes of CNS diseases in man were first found in isolated or socially segregated groups, high incidence TSP focus in Tumaco, Colombia; drug-using mothers in Newark, New Jersey, and are often best studied in these isolated or socially segregated groups. We now have a proto-Melanesian quasispecies of HTLV-I in New Guinea, Solomon Islands, Vanautu of an archaic origin, not associated with monkeys at least for milenia.